The structural design of small aircraft, such as those used in business aviation, differs substantially from that of large commercial aircraft. These relatively small aircraft might be designed to carry from four to six passengers (in addition to the air crew). Of particular importance are the requirements of minimal weight and maximum cabin space. To meet these requirements, the fuselage is preferably constructed of fiber-reinforced composite materials.
When aircraft need to fly at altitudes of more than 25,000 ft., cockpit and cabin compartment must be pressurized. To accomplish this, the pressurized compartments normally have forward and aft bulkheads that separate the pressurized compartment from non-pressurized spaces. The bulkheads must have sufficient strength and rigidity to resist the pressure differential load at altitude.
The shape of a fuselage is generally tubular with a cross section that may be circular or oval, for example. The pressurized compartment is sealed in part by the inner surface of the fuselage and also in part by the pressure bulkhead mounted within the fuselage. The method used to install the pressure bulkhead in the fuselage must be effective to seal against air leakage and to assure maximum strength.
When the cockpit and cabin compartment of the aircraft is pressurized, the pressure force tends to deform the bulkhead outwardly and as a result, the bulkhead must be reinforced to provide adequate strength and stiffness to resist the force. In addition, in order to maximize the usable space in the cabin compartment, the height of the bulkhead assembly should be minimized. In this regard, bulkhead assembly height is the physical dimension of the bulkhead assembly extending from the pressurized compartment to the non-pressurized compartment, and for the aft bulkhead, generally extends in the forward-to-aft direction. The height of the aft bulkhead is especially important in the case of small aircraft wherein cabin space is at a premium.
In most cases, pressure bulkheads for small airplanes consist of a flat web and multiple beams. The flat web has a first surface facing toward the inside of the pressurized compartment and a second, opposite surface facing toward the non-pressurized compartment. The multiple beams, which serve as a reinforcing structure, are attached to the second surface of the flat web. In prior pressure bulkhead designs, sufficient strength has been provided at excessive height of the bulkhead assembly and has resulted in smaller pressurized compartments.
Therefore, there exists a need in the art for an improved design of a pressure bulkhead assembly that provides an assembly with a suitable strength at a reduced height.